This invention relates to a coating apparatus and more particularly to an improved rotary atomizer coater for depositing paint and similar material on a workpiece. The present invention is particularly adaptable for use on a robot mounting.
In one type of prior art coating apparatus for paint and the like, a rotary atomizer, such as a disk or bell is driven by a drive means, such as an air motor. The air motor may be an air driven turbine. It is known in the prior art that a governor may be built to an air turbine for regulating the speed of the turbine output shaft. Such a governor unit is illustrated, for example, in U.S. Pat. No. 3,708,240. The bell is rotated at high speeds, normally between 10,000 and 40,000 rpm.
Paint is delivered to the inner surface of the rapidly rotating bell and is thrown off in small particles through centrifugal force. The surface of the bell is charged to a high voltage, normally between 30 KV and 100 KV to electrostatically charge the paint particles. The atomized charged paint particles are directed at and coat the workpiece by the charge on the paint particles and in some embodiments by a surrounding stream of air discharged from the rotary atomizer coater.
When a rotary atomizer coater is charged to the high voltages required, it is necessary to establish a non-conductive path between the charged, metallic shaft and rotating bell and any grounded object, for example, the arm of an industrial robot.
The high rotational speed of the rotary atomizer bell coupled with the use of coating material and solvents has often created bearing problems in prior art devices.